Electronic devices and mechanical devices currently available will for example additionally arrange an optical encoder inside a driver component of a motor as a conventional technique to accurately grasp the rotation and movement situation between individual components with respect to each other. An optical encoder includes an optical structure having particular information, a light source and a light sensor. Typically, the optical structure has a plurality of areas able to let light pass through. When the optical structure rotates, the light sensor receives a particular periodical light signal, and then the optical encoder may further determine the displacement, the angular displacement and rotation speed of the object driven by the driver component according to the light signal.
Due to the continuously increasing positioning requirements between individual components in current technology, as a result the density of the periodical area of an optical disk in current optical encoders is increasing. However, in order to analyze the light signal formed by the periodical area, the density and positioning accuracy of a sensing device are increasing as a result as well. High density and high positioning accuracy sensing devices increase the manufacturing cost and difficulty, thus limiting the highest positioning resolution determinable by an optical encoder.